Hi!

I am using Elixir 1.18.3 on OTP 27.
Using torchx version 0.10 compiled using LIBTORCH_TARGET=cu128 and LIBTORCH_VERSION=2.9.0

I am trying to hunt down a serious memory leak / no-free situation when using Torchx.
This is very easy to reproduce using the code below.

The issue is that the virtual memory increases in eternity.

image1616×417 2.63 KB

GPU memory is released at intervals as I expect libtorch to do keeping the load at a acceptable level:

image1600×309 2.38 KB

I was hunting down a memory leak in the Ortex library (I thought) but it turned out the problem was in Torchx which I used to prepare som data I sent into Ortex.

defmodule Mix.Tasks.Simple do
  @impl Mix.Task
  def run(_args) do
    10000
    |> runner()
  end

  defp runner(0), do: :ok

  defp runner(ittr) do
    Task.async(fn ->
      tensor =
        Nx.broadcast(0, {1, 3, 640, 640})
        |> Nx.backend_transfer(Nx.default_backend())
    end)
    |> Task.await()

    Process.sleep(50)

    runner(ittr - 1)
  end
end

I have also tried to use :erlang.garbage_collect to try releasing the memory but that does nothing.
I also, as you can see put the code into a Task as I thought maybe the memory was “trapped” in my parent process.
This also did nothing.

Anyone have any ideas?

I would really like to run this in WSL and use EXLA instead, but due to peripherals I have to stay in Windows.